The study, by Alexis Conason, PsyD, of the New York Obesity Research Center, and colleagues also found a link between a specific operation, laparoscopic Roux-en-Y gastric bypass surgery, and an increase in alcohol use after the procedure. The findings appear in the Oct. 15 online issue of Archives of Surgery.

"We're only talking about a minority of patients here," Conason says. "But what we're seeing is some patients who seek out bariatric surgery have a history of using food to deal with emotions."

When such patients no longer can overeat as a way to cope with their feelings, they may turn to "other external coping mechanisms like drugs or alcohol," Conason says.

The study looked at 132 women and 23 men who underwent either Roux-en-Y -- one of the most common weight loss surgeries -- or laparoscopic adjustable gastric band surgery to treat their obesity. Participants answered questionnaires about their behaviors and history of drinking or drugs before their surgery and then again one, three, six, 12, and 24 months after their operations.

"When we looked at each substance (drugs, alcohol, and cigarette smoking) individually, we didn't see a huge difference, but when you looked at the whole group, we saw a significant increased risk for drug and alcohol use at the two-year point after the surgery," says Conason. "Our findings are important because it raises some concerns about who is at risk."

Struggling With a New Body

Nearly 36% of the adult U.S. population is obese. Some 200,000 adults have bariatric surgery each year, according to the American Society for Metabolic and Bariatric Surgery.

Psychological profiles vary among severely obese patients seeking bariatric surgery. Conason says patients' issues range from depression and anxiety to loneliness, difficulty dealing with relationships, and dealing with the social stresses of being obese.

Many bariatric surgery patients may lose 60% of their excess body weight within a year. The change can be emotionally shocking for some patients.